Background and aims: Social network use is widespread, and the study of Instagram seems to have captured more attention in recent years. However, scale development and validation in the field has fallen short of providing sound scales of Instagram motives and usage patterns that consider the uniqueness of Instagram-related behavior. This paper describes the development, psychometric and cross-cultural validation of two new measurement instruments: the ?Instagram Motives Questionnaire" (IMQ) and the ?Instagram Uses and Patterns Questionnaire" (IUPQ). Methods and results: A preliminary set of items was developed for each questionnaire based on a previous qualitative interview study on Instagram motives, uses, and consequences. In the first study, the questionnaires were distributed to a sample of 312 participants aged 18-35 years (M 5 23.81; SD 5 4.49), and an exploratory factor analysis was performed. A parsimonious and interpretable 6-factor solution that displayed adequate factor loadings and adequate Omega coefficients for both instruments were found. In a second study, the two instruments and other measures of known social network usage correlates and mental health consequences were administered online to 1,418 English-speaking participants aged 18-34 years (M 5 21.35; SD 5 3.89). Both scales showed good psychometric properties and the factor structure identified in study 1 was reproduced through confirmatory factor analysis. Omega reliability coefficients were adequate. Finally, when performing multi-group CFA along with a French (n 5 1,826) and a Spanish (n 5 3,040) sample, language and gender invariance were supported. Correlations with other relevant measures indicate good convergent validity of both scales. Conclusions: The present research provides psychometrically sound instruments for further investigations on Instagram use behaviors.  Kulcsszavak: Instagram, youths, motives, patterns of use, consequences, psychometric study, cross-cultural study, measurement invariance